Cross-aldol condensations involving “low reactivity” ketones, i.e., which need strong reaction conditions to react, and/or “high reactivity” aldehydes, i.e., which undergo self-condensation or polymerization even with soft reaction conditions, are difficult processes as, in general, important amounts of strong bases are required and/or the self-condensation or the polymerization of the aldehyde or of the final enone are frequently observed.
An example of existing process for the cross-aldol condensation between a sterically hindered cyclohexylethanone, a “low reactivity” ketone, and acetaldehyde, a “high reactivity” aldehyde, is the one described in Ayyar et al. J. Chem. Soc., Prekin Trans. I, 1975, 17, 1727. However, said method needs the use of a stoichiometric amount of a strong base such as the N-methylanilino magnesium bromide for the formation of an enolate. Strong bases such as an amide anion have the inconvenience of being expensive and difficult to manipulate, therefore a process implying large amounts of base does not represent the best solution for this type of reaction, all the more for an industrial purpose.